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  • Silverlight with MVVM Inheritance: ModelView and View matching the Model

    - by moonground.de
    Hello Stackoverflowers! :) Today I have a special question on Silverlight (4 RC) MVVM and inheritance concepts and looking for a best practice solution... I think that i understand the basic idea and concepts behind MVVM. My Model doesn't know anything about the ViewModel as the ViewModel itself doesn't know about the View. The ViewModel knows the Model and the Views know the ViewModels. Imagine the following basic (example) scenario (I'm trying to keep anything short and simple): My Model contains a ProductBase class with a few basic properties, a SimpleProduct : ProductBase adding a few more Properties and ExtendedProduct : ProductBase adding another properties. According to this Model I have several ViewModels, most essential SimpleProductViewModel : ViewModelBase and ExtendedProductViewModel : ViewModelBase. Last but not least, according Views SimpleProductView and ExtendedProductView. In future, I might add many product types (and matching Views + VMs). 1. How do i know which ViewModel to create when receiving a Model collection? After calling my data provider method, it will finally end up having a List<ProductBase>. It containts, for example, one SimpleProduct and two ExtendedProducts. How can I transform the results to an ObservableCollection<ViewModelBase> having the proper ViewModel types (one SimpleProductViewModel and two ExtendedProductViewModels) in it? I might check for Model type and construct the ViewModel accordingly, i.e. foreach(ProductBase currentProductBase in resultList) if (currentProductBase is SimpleProduct) viewModels.Add( new SimpleProductViewModel((SimpleProduct)currentProductBase)); else if (currentProductBase is ExtendedProduct) viewModels.Add( new ExtendedProductViewModels((ExtendedProduct)currentProductBase)); ... } ...but I consider this very bad practice as this code doesn't follow the object oriented design. The other way round, providing abstract Factory methods would reduce the code to: foreach(ProductBase currentProductBase in resultList) viewModels.Add(currentProductBase.CreateViewModel()) and would be perfectly extensible but since the Model doesn't know the ViewModels, that's not possible. I might bring interfaces into game here, but I haven't seen such approach proven yet. 2. How do i know which View to display when selecting a ViewModel? This is pretty the same problem, but on a higher level. Ended up finally having the desired ObservableCollection<ViewModelBase> collection would require the main view to choose a matching View for the ViewModel. In WPF, there is a DataTemplate concept which can supply a View upon a defined DataType. Unfortunately, this doesn't work in Silverlight and the only replacement I've found was the ResourceSelector of the SLExtensions toolkit which is buggy and not satisfying. Beside that, all problems from Question 1 apply as well. Do you have some hints or even a solution for the problems I describe, which you hopefully can understand from my explanation? Thank you in advance! Thomas

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  • Nservicebus serization issue of derived types

    - by Tiju John
    Hi Guys, for the context setting, I am exchanging messages between my nServiceBus client and nSerivceBus server. its is the namespace xyz.Messages and and a class, Message : IMessage I have more messages that are in the other dlls, like xyz.Messages.Domain1, xyz.Messages.Domain2, xyz.Messages.Domain3. and messages that derive form that base message, Message. I have the endpoints defined as like : at client <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzServerQueue" /> </MessageEndpointMappings> </UnicastBusConfig> at Server <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzClientQueue" /> </MessageEndpointMappings> </UnicastBusConfig> and the bus initialized as IBus serviceBus = Configure.With() .SpringBuilder() .XmlSerializer() .MsmqTransport() .UnicastBus() .LoadMessageHandlers() .CreateBus() .Start(); now when i try sending instance of Message type or any type derived types of Message, it successfully sends the message over and at the server, i get the proper type. eg. Message message= new Message(); Bus.Send(message); // works fine, transfers Message type message = new MessageDerived1(); Bus.Send(message); // works fine, transfers MessageDerived1 type message = new MessageDerived2(); Bus.Send(message); // works fine, transfers MessageDerived2 type My problem arises when any type, say MessageDerived1, contains a member variable of type Message, and when i assign it to a derived type, the type is not properly transferred over the wire. It transfers only as Message type, not the derived type. public class MessageDerived2 : Message { public Message message; } MessageDerived2 messageDerived2= new MessageDerived2(); messageDerived2.message = new MessageDerived1(); message = messageDerived2; Bus.Send(message); // incorrect behaviour, transfers MessageDerived2 correctly, but looses type of MessageDerived2.Message (it deserializes as Message type, instead of MessageDerived1) any help is strongly appreciated. Thanks TJ

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  • Opinion on "loop invariants", and are these frequently used in the industry?

    - by Michael Aaron Safyan
    I was thinking back to my freshman year at college (five years ago) when I took an exam to place-out of intro-level computer science. There was a question about loop invariants, and I was wondering if loop invariants are really necessary in this case or if the question was simply a bad example... the question was to write an iterative definition for a factorial function, and then to prove that the function was correct. The code that I provided for the factorial function was as follows: public static int factorial(int x) { if ( x < 0 ){ throw new IllegalArgumentException("Parameter must be = 0"); }else if ( x == 0 ){ return 1; }else{ int result = 1; for ( int i = 1; i <= x; i++ ){ result*=i; } return result; } } My own proof of correctness was a proof by cases, and in each I asserted that it was correct by definition (x! is undefined for negative values, 0! is 1, and x! is 1*2*3...*x for a positive value of x). The professor wanted me to prove the loop using a loop invariant; however, my argument was that it was correct "by definition", because the definition of "x!" for a positive integer x is "the product of the integers from 1... x", and the for-loop in the else clause is simply a literal translation of this definition. Is a loop invariant really needed as a proof of correctness in this case? How complicated must a loop be before a loop invariant (and proper initialization and termination conditions) become necessary for a proof of correctness? Additionally, I was wondering... how often are such formal proofs used in the industry? I have found that about half of my courses are very theoretical and proof-heavy and about half are very implementation and coding-heavy, without any formal or theoretical material. How much do these overlap in practice? If you do use proofs in the industry, when do you apply them (always, only if it's complicated, rarely, never)?

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  • Menu Control in Master Page fails to use CSS styles

    - by Shaun
    I'm working on a web application that uses ASP.NET 3.5 and C#. Structurally, I have a master page with a menu control on it. The control serves as my navigation, and it gets its items from a SiteMapDataSource control and a corresponding Web.sitemap file. The problem is that some styles do not render properly when you specify the CssClass property. More specifically, the selected and hover styles don't respond to css styles. Consider the code below: <%@ Master Language="C#" AutoEventWireup="true" CodeFile="Site.master.cs" Inherits="Site" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.or/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>A webpage</title> </head> <body> <form id="form1" runat="server"> <div id="page"> <asp:Menu ID="navMenu" Orientation="Horizontal" StaticMenuStyle-CssClass="staticMenu" StaticMenuItemStyle-CssClass="staticMenuItem" StaticSelectedStyle-CssClass="staticSelectedItem" StaticHoverStyle-CssClass="staticHoverItem" runat="server"> </asp:Menu> <asp:SiteMapDataSource ID="srcSiteMap" runat="server" ShowStartingNode="false" /> <br /> <asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server"> </asp:ContentPlaceHolder> </div> </form> </body> </html> Suppose I had a corresponding .css file with the following: .staticMenuItem { background-color:Red; } .staticSelectedItem { background-color:Green; } .staticHoverItem { background-color:Blue; } What will happen is that my item backgrounds will properly be red, but my selected item will not be green and the item I'm hovering my mouse over will not be blue. This seems true regardless of whether or not I include the style in the head of the master page or in an external file in default theme as specified in the web.config file. If I specify the styles in the asp.net xml like so: <asp:Menu ID="navMenu" Orientation="Horizontal" runat="server"> <StaticSelectedStyle BackColor="Green" Font-Underline="True" Font-Bold="True" /> <StaticHoverStyle BackColor="Gray" /> </asp:Menu> It appears to work properly in Firefox, but the style is never embedded in the html in Internet Explorer. Odd. Does anybody have any insight into what is causing this problem and how to neatly work around it? I'm aware I might be able to programmically determine the current page and select the corresponding menu item manually so it receives the proper style class, but before I resort to hacking C# and Javascript together to fix this functionality, I'm open to ideas.

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  • GAE Datastore: persisting referenced objects

    - by David
    Two "I'm sorries" to begin with: 1) I've looked for a solution (here, and elsewhere), and couldn't find the answer. 2) English is not my mother tongue, so I may have some typos and the sort - please ignore them. To the point: I am trying to persist Java objects to the GAE datastore. I am not sure as to how to persist object having ("non-trivial") referenced object. That is, assume I have the following. public class Father { String name; int age; Vector<Child> offsprings; //this is what I call "non-trivial" reference //ctor, getters, setters... } public class Child { String name; int age; Father father; //this is what I call "non-trivial" reference //ctor, getters, setters... } The name field is unique in each type domain, and is considered a Primary-Key. In order to persist the "trivial" (String, int) fields, all I need is to add the correct annotation. So far so good. However, I don't understand how should I persist the home-brewed (Child, Father) types referenced. Should I: Convert each such reference to hold the Primary-Key (a name String, in this example) instead of the "actual" object. So, Vector<Child> offsprings; becomes Vector<String> offspringsNames; ? If that is the case, how do I handle the object at run-time? Do I just query for the Primary-Key from Class.getName, to retrieve the refrenced objects? Convert each such reference to hold the actual Key provided to me by the Datastore upon the proper put() operation? So, Vector<Child> offsprings; becomes Vector<Key> offspringsHashKeys; ? I would very much appreciate all kinds of comments. I have read ALL the offical relevant GAE docs/example. Throughout, they always persist "trivial" references, natively supported by the Datastore (e.g. in the Guestbook example, only Strings, and Longs). Many thanks, David

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  • Creating a spam list with a web crawler in python

    - by user313623
    Hey guys, I'm not trying to do anything malicious here, I just need to do some homework. I'm a fairly new programmer, I'm using python 3.0, and I having difficulty using recursion for problem-solving. I've been stuck on this question for quite a while. Here's the assignment: Write a recursive method spam(url, n) that takes a url of a web page as input and a non-negative integer n, collects all the email address contained in the web page and adds them to a global dictionary variable spam_dict, and then recursively calls itself on every http hyperlink contained in the web page. You will use a dictionary so only one copy of every email address is save; your dictionary will store (key,value) pairs (email, email). The recursive call should use the parameter n-1 instead of n. If n = 0, you should collect the email addresses but no recursive calls should be made. The parameter n is used to limit the recursion to at most depth n. You will need to use the solutions of the two above problems; you method spam() will call the methods links2() and emails() and possibly other functions as well. Notes: 1. running spam() directly will produce no output on the screen; to find your spam_dict, you will need to read the value of spam_dict, and you will also need to reset it to the empty dictionary before every run of spam. 2. Recall how global variables are used. Usage: spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',0) spam_dict.keys() dict_keys([]) spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',1) spam_dict.keys() dict_keys(['[email protected]', '[email protected]']) So far, I've written a function that traverses web pages and puts all the links in a nice little list, and what I wanted to do was call that functions. And why would I use recursion on a dictionary? And how? I don't understand how n ties into all of this. def links2(url): content = str(urlopen(url).read()) myparser = MyHTMLParser() myparser.feed(content) lst = myparser.get() mergelst = [] for link in lst: mergelst.append(urljoin(lst[0],link)) print(mergelst) Any input (except why spam is bad) would be greatly appreciated. Also, I realize that the above function could probably look better, if you have a way to do it, I'm all ears. However, all I need is the point is for the program to produce the proper output.

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  • Do you feel underappreciated or resent the geek/nerd stigma?

    - by dotnetdev
    At work we have a piece of A4 paper with the number of everyone in the office. The structure of this document is laid out in rectangles, by department. I work for the department that does all the technical stuff. That includes support—bear in mind that the support staff isn't educated in IT but just has experience in PC maintenance and providing support to a system we resell but don't have source code access to, project manager, team leader, a network administrator, a product manager, and me, a programmer. Anyway, on this paper, we are labelled as nerds and geeks. I did take a little offence to this, as much as it is light hearted (but annoying and old) humour. I have a vivid image that a geek is someone who doesn't go out but codes all day. I code all day at home and at work (when I have something to code...), but I keep balance by going out. I don't know why it is only people who work with computers that get such a stigma. No other profession really gets the same stigma—skilled, technical, or whatever. An account manager (and this is hardly a skilled job) says, "Perhaps [MY NAME HERE] could write some geeky code tomorrow to add this functionality to the website." It is funny how I get such an unfair stigma but I am so pivotal. In fact, if it wasn't for me, the company would have nothing to sell so the account managers would be redundant! I make systems, they get sold, and this is what pays the wages. It's funny how the account managers get a commission for how many systems they sell, or manage to make clients resubscribe to. Yet I built the thing in the first place! On top of that, my brother says all I do is type stuff on a keyboard all day. Surely if I did, I'd be typing at my normal typing speed of 100wpm+ as if I am writing a blog entry. Instead, I plan as I code along on the fly if commercial pressures and time prohibit proper planning. I never type as if I'm writing normal English. There is more to our jobs than just typing code. And my brother is a pipe fitter with no formal qualifications in his name. I could easily, and perhaps more justifiably, say he just manipulates a spanner or something. Does you feel underappreciated or that a geek/nerd stigma is undeserved or unfair?

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  • Optimize date query for large child tables: GiST or GIN?

    - by Dave Jarvis
    Problem 72 child tables, each having a year index and a station index, are defined as follows: CREATE TABLE climate.measurement_12_013 ( -- Inherited from table climate.measurement_12_013: id bigint NOT NULL DEFAULT nextval('climate.measurement_id_seq'::regclass), -- Inherited from table climate.measurement_12_013: station_id integer NOT NULL, -- Inherited from table climate.measurement_12_013: taken date NOT NULL, -- Inherited from table climate.measurement_12_013: amount numeric(8,2) NOT NULL, -- Inherited from table climate.measurement_12_013: category_id smallint NOT NULL, -- Inherited from table climate.measurement_12_013: flag character varying(1) NOT NULL DEFAULT ' '::character varying, CONSTRAINT measurement_12_013_category_id_check CHECK (category_id = 7), CONSTRAINT measurement_12_013_taken_check CHECK (date_part('month'::text, taken)::integer = 12) ) INHERITS (climate.measurement) CREATE INDEX measurement_12_013_s_idx ON climate.measurement_12_013 USING btree (station_id); CREATE INDEX measurement_12_013_y_idx ON climate.measurement_12_013 USING btree (date_part('year'::text, taken)); (Foreign key constraints to be added later.) The following query runs abysmally slow due to a full table scan: SELECT count(1) AS measurements, avg(m.amount) AS amount FROM climate.measurement m WHERE m.station_id IN ( SELECT s.id FROM climate.station s, climate.city c WHERE -- For one city ... -- c.id = 5182 AND -- Where stations are within an elevation range ... -- s.elevation BETWEEN 0 AND 3000 AND 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 ) AND -- -- Begin extracting the data from the database. -- -- The data before 1900 is shaky; insufficient after 2009. -- extract( YEAR FROM m.taken ) BETWEEN 1900 AND 2009 AND -- Whittled down by category ... -- m.category_id = 1 AND m.taken BETWEEN -- Start date. (extract( YEAR FROM m.taken )||'-01-01')::date AND -- End date. Calculated by checking to see if the end date wraps -- into the next year. If it does, then add 1 to the current year. -- (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date GROUP BY extract( YEAR FROM m.taken ) The sluggishness comes from this part of the query: m.taken BETWEEN /* Start date. */ (extract( YEAR FROM m.taken )||'-01-01')::date AND /* End date. Calculated by checking to see if the end date wraps into the next year. If it does, then add 1 to the current year. */ (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date The HashAggregate from the plan shows a cost of 10006220141.11, which is, I suspect, on the astronomically huge side. There is a full table scan on the measurement table (itself having neither data nor indexes) being performed. The table aggregates 237 million rows from its child tables. Question What is the proper way to index the dates to avoid full table scans? Options I have considered: GIN GiST Rewrite the WHERE clause Separate year_taken, month_taken, and day_taken columns to the tables What are your thoughts? Thank you!

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  • Django Encoding Issues with MySQL

    - by Jordan Reiter
    Okay, so I have a MySQL database set up. Most of the tables are latin1 and Django handles them fine. But, some of them are UTF-8 and Django does not handle them. Here's a sample table (these tables are all from django-geonames): DROP TABLE IF EXISTS `geoname`; SET @saved_cs_client = @@character_set_client; SET character_set_client = utf8; CREATE TABLE `geoname` ( `id` int(11) NOT NULL, `name` varchar(200) NOT NULL, `ascii_name` varchar(200) NOT NULL, `latitude` decimal(20,17) NOT NULL, `longitude` decimal(20,17) NOT NULL, `point` point default NULL, `fclass` varchar(1) NOT NULL, `fcode` varchar(7) NOT NULL, `country_id` varchar(2) NOT NULL, `cc2` varchar(60) NOT NULL, `admin1_id` int(11) default NULL, `admin2_id` int(11) default NULL, `admin3_id` int(11) default NULL, `admin4_id` int(11) default NULL, `population` int(11) NOT NULL, `elevation` int(11) NOT NULL, `gtopo30` int(11) NOT NULL, `timezone_id` int(11) default NULL, `moddate` date NOT NULL, PRIMARY KEY (`id`), KEY `country_id_refs_iso_alpha2_e2614807` (`country_id`), KEY `admin1_id_refs_id_a28cd057` (`admin1_id`), KEY `admin2_id_refs_id_4f9a0f7e` (`admin2_id`), KEY `admin3_id_refs_id_f8a5e181` (`admin3_id`), KEY `admin4_id_refs_id_9cc00ec8` (`admin4_id`), KEY `fcode_refs_code_977fe2ec` (`fcode`), KEY `timezone_id_refs_id_5b46c585` (`timezone_id`), KEY `geoname_52094d6e` (`name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; SET character_set_client = @saved_cs_client; Now, if I try to get data from the table directly using MySQLdb and a cursor, I get the text with the proper encoding: >>> import MySQLdb >>> from django.conf import settings >>> >>> conn = MySQLdb.connect (host = "localhost", ... user = settings.DATABASES['default']['USER'], ... passwd = settings.DATABASES['default']['PASSWORD'], ... db = settings.DATABASES['default']['NAME']) >>> cursor = conn.cursor () >>> cursor.execute("select name from geoname where name like 'Uni%Hidalgo'"); 1L >>> g = cursor.fetchone() >>> g[0] 'Uni\xc3\xb3n Hidalgo' >>> print g[0] Unión Hidalgo However, if I try to use the Geoname model (which is actually a django.contrib.gis.db.models.Model), it fails: >>> from geonames.models import Geoname >>> g = Geoname.objects.get(name__istartswith='Uni',name__icontains='Hidalgo') >>> g.name u'Uni\xc3\xb3n Hidalgo' >>> print g.name Unión Hidalgo There's pretty clearly an encoding error here. In both cases the database is returning 'Uni\xc3\xb3n Hidalgo' but Django is (incorrectly?) translating the '\xc3\xb3n' to ó. What can I do to fix this?

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  • Available Coroutine Libraries in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7? Edited to add: Just to ensure that confusion is contained, this is a related question to my other one, but not the same. This one is looking for an existing implementation in a bid to avoid reinventing the wheel unnecessarily. The other one is a question relating to how one would go about implementing coroutines in Java should this question prove unanswerable. The intent is to keep different questions on different threads.

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  • Recommendations for a free GIS library supporting raster images

    - by gspr
    Hi. I'm quite new to the whole field of GIS, and I'm about to make a small program that essentially overlays GPS tracks on a map together with some other annotations. I primarily need to allow scanned (thus raster) maps (although it would be nice to support proper map formats and something like OpenStreetmap in the long run). My first exploratory program uses Qt's graphics view framework and overlays the GPS points by simply projecting them onto the tangent plane to the WGS84 ellipsoid at a calibration point. This gives half-decent accuracy, and actually looks good. But then I started wondering. To get the accuracy I need (i.e. remove the "half" in "half-decent"), I have to correct for the map projection. While the math is not a problem in itself, supporting many map projection feels like needless work. Even though a few projections would probably be enough, I started thinking about just using something like the PROJ.4 library to do my projections. But then, why not take it all the way? Perhaps I might aswell use a full-blown map library such as Mapnik (edit: Quantum GIS also looks very nice), which will probably pay off when I start to want even more fancy annotations or some other symptom of featuritis. So, finally, to the question: What would you do? Would you use a full-blown map library? If so, which one? Again, it's important that it supports using (and zooming in and out with) raster maps and has pretty overlay features. Or would you just keep it simple, and go with Qt's own graphics view framework together with something like PROJ.4 to handle the map projections? I appreciate any feedback! Some technicalities: I'm writing in C++ with a Qt-based GUI, so I'd prefer something that plays relatively nicely with those. Also, the library must be free software (as in FOSS), and at least decently cross-platform (GNU/Linux, Windows and Mac, at least). Edit: OK, it seems I didn't do quite enough research before asking this question. Both Quantum GIS and Mapnik seem very well suited for my purpose. The former especially so since it's based on Qt.

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  • PostgreSQL - fetch the row which has the Max value for a column

    - by Joshua Berry
    I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

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  • Serious Memory Clash: Variables clashing in C

    - by Soham
    int main(int argc, char*argv[]) { Message* newMessage; Asset* Check; //manipulation and initialization of Check, so that it holds proper values. newMessage = parser("N,2376,01/02/2011 09:15:01.342,JPASSOCIAT FUTSTK 24FEB2011,B,84.05,2000,0,0",newMessage); // MessageProcess(newMessage,AssetMap); printf("LAST TRADE ADDRESS %p LAST TRADE TIME %s\n",Check->TradeBook,Check->Time); } Message* parser(char *message,Message* new_Message) { char a[9][256]; char* tmp =message; bool inQuote=0; int counter=0; int counter2=0; new_Message = (Message*)malloc(sizeof(Message)); while(*tmp!='\0') { switch(*tmp) { case ',': if(!inQuote) { a[counter][counter2]='\0'; counter++; counter2=0; } break; case '"': inQuote=!inQuote; break; default: a[counter][counter2]=*tmp; counter2++; break; } tmp++; } a[counter][counter2]='\0'; new_Message->type = *a[0]; new_Message->Time = &a[2][11]; new_Message->asset = a[3]; if(*a[4]=='S') new_Message->BS = 0; else new_Message->BS = 1; new_Message->price1=atof(a[5]); new_Message->shares1=atol(a[6]); new_Message->price2=atof(a[7]); new_Message->shares2=atol(a[8]); new_Message->idNum = atoi(a[1]); return(new_Message); } Here there is a serious memory clash, in two variables of different scope. I have investigated using gdb and it seems the address of new_Message->Time is equalling to the address of Check->Time. They both are structures of different types I am trying to resolve this issue, because, when parser changes the value of new_Message->Time it manipulates the contents of Check-Time Please do suggest how to solve this problem. I have lost(spent) around 10 hours and counting to resolve this issue, and tons of hair. Soham

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  • JavaScript accessing form elements using document.forms[].elements[]

    - by thecoshman
    var loc_name = document.forms['create_<?php echo(htmlspecialchars($window_ID)); ?>'].elements['location_name']; alert(loc_name); This just gives me the message 'undefined' where as... var loc_name = document.forms['create_<?php echo(htmlspecialchars($window_ID)); ?>']; alert(loc_name); Gives me the object form business. Have I just got this all wrong? What is the 'proper' way to access this form element. The form element has the correct name and it has an id, the id is similar but not the same. ** HTML - as reuqested ** <form action="javascript:void(0)" name="create_<?php echo(htmlspecialchars($window_ID)); ?>" method="GET" onsubmit="return false"> <td> <input type="text" id="location_name_<?php echo($window_ID); ?>" name="location_name" value="Enter a name" onfocus="if(this.value == 'Enter a name'){this.value = ''}" onblur="if(this.value == ''){ this.value = 'Enter a name' }" /> </td> <td colspan="2"> <input type="button" name="create_location" value="Create" onclick="var pre_row_was = $('#pre_form_row_<?php echo($window_ID); ?>').innerHTML; $('#pre_form_row_<?php echo($window_ID); ?>').innerHTML = '<td colspan=\'3\'>Validating...</td>'; var loc_name = document.forms['create_<?php echo(htmlspecialchars($window_ID)); ?>'].elements['location_name']; alert(loc_name); if(loc_name.value == '') { alert('You can\'t leave the room name blank'); loc_name.focus(); loc_name.value = 'Enter a name'; $('#pre_form_row_<?php echo($window_ID); ?>').innerHTML = pre_row_was; return false; } if(loc_name.value == 'Enter a name') { alert('You must enter a room name first'); loc_name.focus(); $('#pre_form_row_<?php echo($window_ID); ?>').innerHTML = pre_row_was; return false; } $('#pre_form_row_<?php echo($window_ID); ?>').innerHTML = pre_row_was; Window_manager.new_window().load_xml('location/create.php?location_name=' + loc_name.value).display();" /> </td> </form> ugly as sin that is...

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  • Android - Transforming widgets within transformed widgets and the resulting usability issues.

    - by Ben Rose
    Hello. I'm new to Android application development and I'm currently experimenting with various UI ideas. In the image below, you can see a vertically scrolling list of horizontally scrolling galleries (and also textviews as you can see). I'm also doing some matrix and camera transformations which I will come to in a minute. For the background of the list elements, I use green. Blue is the background of the galleries, and red is the background for the images. These are just for my benefit of learning. The galleries being used are extended classes where I overrode the drawChild method to perform a canvas scale operation in order for the image closest to the center (width) to be larger than the others. The list view going vertically, I overrode the drawChild method and used the camera rotations from lack of depth dimension in the canvas functionality. The items in the list are scaled down and rotated relative to their position's proximity to the center (height). I understood that scrolling and clicking would not necessarily follow along with the image transforms, but it appears as though the parent Gallery class's drawing is constrained to the original coordinates as well (see photo below). I would love to hear any insight any of you have regarding how I can change the coordinates of the galleries in what is rendered via gallery scroll and the touch responsiveness of said gallery. Images in the gallery are not same dimensions, so don't let that throw you in looking at the image below Thanks in advance! Ben link to image (could not embed) -- Update: I was using my test application UI and noticed that when I got the UI to the point of the linked image and then I touched the top portion of the next row in the list, the gallery updated to display the proper representation. So, I added a call to clearFocus() in the drawChild method and that resulted in more accurate drawing. It does seem a tad slower, and since I'm on the Incredible, I'm worried it is a bloated solution. In any event, I would still appreciate any thoughts you have regarding the best way to have the views display properly and how to translate the touch events in the gallery's new displayed area to its touchable coordinates so that scrolling on the actual images works when the gallery has moved. Thanks!

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  • How to measure a canvas that has auto height and with

    - by Wymmeroo
    Hi Folks, I'm a beginner in silverlight so i hope i can get an answer that brings me some more light in the measure process of silverlight. I found an interessting flap out control from silverlight slide control and now I try to use it in my project. So that the slide out is working proper, I have to place the user control on a canvas. The user control then uses for itself the height of its content. I just wanna change that behavior so that the height is set to the available space from the parent canvas. You see the uxBorder where the height is set. How can I measure the actual height and set it to the border? I tried it with Height={Binding ElementName=notificationCanvas, Path=ActualHeight} but this dependency property has no callback, so the actualHeight is never set. What I want to achieve is a usercontrol like the tweetboard per example on Jesse Liberty's blog Sorry for my English writing, I hope you understand my question. <Canvas x:Name="notificationCanvas" Background="Red"> <SlideEffectEx:SimpleSlideControl GripWidth="20" GripTitle="Task" GripHeight="100"> <Border x:Name="uxBorder" BorderThickness="2" CornerRadius="5" BorderBrush="DarkGray" Background="DarkGray" Padding="5" Width="300" Height="700" > <StackPanel> <TextBlock Text="Tasks"></TextBlock> <Button x:Name="btn1" Margin="5" Content="{Binding ElementName=MainBorder, Path=Height}"></Button> <Button x:Name="btn2" Margin="5" Content="Second Button"></Button> <Button x:Name="btn3" Margin="5" Content="Third Button"></Button> <Button x:Name="btn1_Copy" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy1" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy2" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy3" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy4" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy5" Margin="5" Content="First Button"/> <Button x:Name="btn1_Copy6" Margin="5" Content="First Button"/> </StackPanel> </Border> </SlideEffectEx:SimpleSlideControl>

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  • On Mac, two jpg's whose color should match do not

    - by Tim
    So I'm designing a myspace page and I have two images, one is a repeating bg image, and another is an image which loads on a layer above it, which acts as a header/masthead. For some reason, on Macs only, and only in the browser (tested in safari and ff), the masthead renders slightly darker than the repeating bg image, creating this color inconsistency. The block that extends up behind the album artwork is a solid box made with css which blocks some of myspace's standard content. It actually renders as the proper color, blending in well with the bottom portion of this image, which is the repeating part of the background, but becomes noticeable as it extends up, over the masthead, which is darker than it should be. Both images where created in GIMP and saved as jpg's using, as far as i can tell, the same settings. Here's the pic of what is going on: Screenshot - Click Me!!! Here is the code which controls this part of the design. <div class="masthead"><span></span></div> .masthead {width: 1600px; height: 1940px; background-image:url(http://www.sourtricks.com/myspace/bdww/myspace_bg09.jpg); position: absolute; margin-left: -800px; left: 50%; top: 0px; z-index: -1; overflow-x: hidden;} body.bodyContent{ margin: 0 !important; padding: 0 !important; background-color: 000000 !important; font-size: 1px; background-image: url(http://www.sourtricks.com/myspace/bdww/bg_repeat05.jpg); background-position: center bottom; _background-position: right bottom; background-attachment: scroll; background-repeat: repeat-y; z-index: -2; overflow-x: hidden; font-family: arial, sans-serif !important; } Any help would be much, much, much appreciated. Thanks for your time, Tim

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  • Crashes in Core Data's Inferred Mapping Model Creation (Lightweight Migration). Threading Issue?

    - by enchilada
    I'm getting random crashes when creating an inferred mapping model (with Core Data's lightweight migration) within my application. By the way, I have to do it programmatically in my application while it is running. This is how I create this model (after I have made proper currentModel and newModel objects, of course): NSMappingModel *mappingModel = [NSMappingModel inferredMappingModelForSourceModel:currentModel destinationModel:newModel error:&error]; The problem is this: This method is crashing randomly. When it works, it works just fine without issues. But when it crashes, it crashes my application (instead of returning nil to signify that the method failed, as it should). By randomly, I mean that sometimes it happens and sometimes not. It is unpredictable. Now, here is the deal: I'm running this method in another thread. More precisely, it is located inside a block that is passed via GCD to run on the global main queue. I need to do this for my UI to appear crisp to the user, i.e. so that I can display a progress indicator while the work is underway. The strange thing seems to be that if I remove the GCD stuff and just let it run on the main thread, it seems to be working fine and never crashing. Thus, could it be because I'm running this on a different thread that this is crashing? I somehow find that weird because I don't believe I'm breaking any Core Data rules regarding multi-threading. In particular, I'm not passing any managed objects around, and whenever I need access to the MOC, I create a new MOC, i.e. I'm not relying on any MOC (or for that matter: anything) that has been created earlier on the main thread. Besides the little MOC stuff that occurs, occurs after the mapping model creation method, i.e. after the point at which the app crashes, so it can't possibly be a cause of the crashes under consideration here. All I'm doing is taking two MOMs and asking for a mapping model between them. That can't be wrong even under threading, now can it? Any ideas on what could be going on?

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  • .NET unit test runner outputting FaultException.Detail

    - by Adam
    Hello, I am running some unit tests on a WCF service. The service is configured to include exception details in the fault response (with the following in my service configuration file). <serviceDebug includeExceptionDetailInFaults="true" /> If a test causes an unhandled exception on the server the fault is received by the client with a fully populated server stack trace. I can see this by calling the exception's ToString() method. The problem is that this doesn't seem to be output by any of the test runners that I have tried (xUnit, Gallio, MSTest). They appear to just output the Message and the StackTrace properties of the exception. To illustrate what I mean, the following unit test run by MSTest would output three sections: Error Message Error Stack Trace Standard Console Output (contains the information I would like, e.g. "Fault Detail is equal to An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is: ..." try { service.CallMethodWhichCausesException(); } catch (Exception ex) { Console.WriteLine(ex); // this outputs the information I would like throw; } Having this information will make the initial phase of testing and deployment a lot less painful. I know I can just wrap each unit test in a generic exception handler and write the exception to the console and rethrow (as above) within all my unit tests but that seems a very long-winded way of achieving this (and would look pretty awful). Does anyone know if there's any way to get this information included for free whenever an unhandled exception occurs? Is there a setting that I am missing? Is my service configuration lacking in proper fault handling? Perhaps I could write some kind of plug-in / adapter for some unit testing framework? Perhaps theres a different unit testing framework which I should be using instead! My actual set-up is xUnit unit tests executed via Gallio for the development environment, but I do have a separate suite of "smoke tests" written which I would like to be able to have our engineers run via the xUnit GUI test runner (or Gallio or whatever) to simplify the final deployment. Thanks. Adam

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  • Who calls the Destructor of the class when operator delete is used in multiple inheritance.

    - by dicaprio-leonard
    This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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  • HTML5 <audio> Safari live broadcast vs not

    - by Peter Parente
    I'm attempting to embed an HTML5 audio element pointing to MP3 or OGG data served by a PHP file . When I view the page in Safari, the controls appear, but the UI says "Live Broadcast." When I click play, the audio starts as expected. Once it ends, however, I can't start it playing again by clicking play. Even using the JS API on the audio element and setting currentTime to 0 fails with an index error exception. I suspected the headers from the PHP script were the problem, particularly missing a content length. But that's not the case. The response headers include a proper Content- Length to indicate the audio has finite size. Furthermore, everything works as expected in Firefox 3.5+. I can click play on the audio element multiple times to hear the sound replay. If I remove the PHP script from the equation and serve up a static copy of the MP3 file, everything works fine in Safari. Does this mean Safari is treating audio src URLs with query parameters differently than URLs that don't have them? Anyone have any luck getting this to work? My simple example page is: <!DOCTYPE html> <html> <head></head> <body> <audio controls autobuffer> <source src="say.php?text=this%20is%20a%20test&format=.ogg" /> <source src="say.php?text=this%20is%20a%20test&format=.mp3" /> </audio> </body> </html> HTTP Headers from PHP script: HTTP/1.x 200 OK Date: Sun, 03 Jan 2010 15:39:34 GMT Server: Apache X-Powered-By: PHP/5.2.10 Content-Length: 8993 Keep-Alive: timeout=2, max=98 Connection: Keep-Alive Content-Type: audio/mpeg HTTP Headers from direct file access: HTTP/1.x 200 OK Date: Sun, 03 Jan 2010 20:06:59 GMT Server: Apache Last-Modified: Sun, 03 Jan 2010 03:20:02 GMT Etag: "a404b-c3f-47c3a14937c80" Accept-Ranges: bytes Content-Length: 8993 Keep-Alive: timeout=2, max=100 Connection: Keep-Alive Content-Type: audio/mpeg I tried hard-coding the Accept-Ranges header into the script too, but no luck.

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  • Beginning with event listeners

    - by terence6
    I have a simple app, showing picture made of tiled images(named u1, u2,...,u16.jpg). Now I'd like to add some Events to it, so that I can show these images only when proper button is clicked. I've tried doing it on my own, but it's not working. Where am I doing something wrong? Original code : import java.awt.GridLayout; import javax.swing.*; import javax.swing.border.BevelBorder; public class Tiles_2 { public static void main(String[] args) { final JFrame f = new JFrame("Usmiech"); JPanel panel = new JPanel(new GridLayout(4, 4, 3, 3)); JLabel l = new JLabel(); for (int i = 1; i < 17; i++) { String path = "u"+ i+".jpg"; l = new JLabel(new ImageIcon(path)); l.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED)); panel.add(l); } f.setContentPane(panel); f.setSize(300, 300); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); } } New code : import java.awt.GridLayout; import javax.swing.*; import javax.swing.border.BevelBorder; import java.awt.event.*; public class Zad_8_1 implements ActionListener { public void actionPerformed(ActionEvent e) { JButton b = (JButton)(e.getSource()); String i = b.getText(); b = new JButton(new ImageIcon("u"+i+".jpg")); } public static void main(String[] args) { final JFrame f = new JFrame("Smile"); JPanel panel = new JPanel(new GridLayout(4, 4, 3, 3)); JButton l = null; for (int i = 1; i < 17; i++) { String path = "u"+ i+".jpg"; l = new JButton(""+i); l.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED)); l.setSize(53,53); panel.add(l); } f.setContentPane(panel); f.setSize(300, 300); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); } } This should work like this : http://img535.imageshack.us/img535/3129/lab8a.jpg

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  • Coroutines in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7?

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  • Objective-c design advice for use of different data sources, swapping between test and live

    - by user200341
    I'm in the process of designing an application that is part of a larger piece of work, depending on other people to build an API that the app can make use of to retrieve data. While I was thinking about how to setup this project and design the architecture around it, something occurred to me, and I'm sure many people have been in similar situations. Since my work is depending on other people to complete their tasks, and a test server, this slows work down at my end. So the question is: What's the best practice for creating test repositories and classes, implementing them, and not having to depend on altering several places in the code to swap between the test classes and the actual repositories / proper api calls. Contemplate the following scenario: GetDataFromApiCommand *getDataCommand = [[GetDataFromApiCommand alloc]init]; getDataCommand.delegate = self; [getDataCommand getData]; Once the data is available via the API, "GetDataFromApiCommand" could use the actual API, but until then a set of mock data could be returned upon the call of [getDataCommand getData] There might be multiple instances of this, in various places in the code, so replacing all of them wherever they are, is a slow and painful process which inevitably leads to one or two being overlooked. In strongly typed languages we could use dependency injection and just alter one place. In objective-c a factory pattern could be implemented, but is that the best route to go for this? GetDataFromApiCommand *getDataCommand = [GetDataFromApiCommandFactory buildGetDataFromApiCommand]; getDataCommand.delegate = self; [getDataCommand getData]; What is the best practices to achieve this result? Since this would be most useful, even if you have the actual API available, to run tests, or work off-line, the ApiCommands would not necessarily have to be replaced permanently, but the option to select "Do I want to use TestApiCommand or ApiCommand". It is more interesting to have the option to switch between: All commands are test and All command use the live API, rather than selecting them one by one, however that would also be useful to do for testing one or two actual API commands, mixing them with test data. EDIT The way I have chosen to go with this is to use the factory pattern. I set up the factory as follows: @implementation ApiCommandFactory + (ApiCommand *)newApiCommand { // return [[ApiCommand alloc]init]; return [[ApiCommandMock alloc]init]; } @end And anywhere I want to use the ApiCommand class: GetDataFromApiCommand *getDataCommand = [ApiCommandFactory newApiCommand]; When the actual API call is required, the comments can be removed and the mock can be commented out. Using new in the message name implies that who ever uses the factory to get an object, is responsible for releasing it (since we want to avoid autorelease on the iPhone). If additional parameters are required, the factory needs to take these into consideration i.e: [ApiCommandFactory newSecondApiCommand:@"param1"]; This will work quite well with repositories as well.

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  • using '.each' method: how do I get the indexes of multiple ordered lists to each begin at [0]?

    - by shecky
    I've got multiple divs, each with an ordered list (various lengths). I'm using jquery to add a class to each list item according to its index (for the purpose of columnizing portions of each list). What I have so far ... <script type="text/javascript"> /* Objective: columnize list items from a single ul or ol in a pre-determined number of columns 1. get the index of each list item 2. assign column class according to li's index */ $(document).ready(function() { $('ol li').each(function(index){ // assign class according to li's index ... index = li number -1: 1-6 = 0-5; 7-12 = 6-11, etc. if ( index <= 5 ) { $(this).addClass('column-1'); } if ( index > 5 && index < 12 ) { $(this).addClass('column-2'); } if ( index > 11 ) { $(this).addClass('column-3'); } // add another class to the first list item in each column $('ol li').filter(function(index) { return index != 0 && index % 6 == 0; }).addClass('reset'); }); // closes li .each func }); // closes doc.ready.func </script> ... succeeds if there's only one list; when there are additional lists, the last column class ('column-3') is added to all remaining list items on the page. In other words, the script is presently indexing continuously through all subsequent lists/list items, rather than being re-set to [0] for each ordered list. Can someone please show me the proper method/syntax to correct/amend this, so that the script addresses/indexes each ordered list anew? many thanks in advance. shecky p.s. the markup is pretty straight-up: <div class="tertiary"> <h1>header</h1> <ol> <li><a href="#" title="a link">a link</a></li> <li><a href="#" title="a link">a link</a></li> <li><a href="#" title="a link">a link</a></li> </ol> </div><!-- END div class="tertiary" -->

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